In a statement to The Register BT has confirmed the legal action alleging that the named companies have infringed its patents in its "blown cable patent portfolio".

The company said: "BT takes the protection of its extensive and valuable intellectual property assets very seriously.

"We've approached the companies concerned over the use of the blown cable patent but in the absence of satisfactory responses have litigated to enforce our rights."

BT's "blown cable" technology uses compressed air and other gasses to blow fibre optic cables down conduits, as opposed to pulling them through using ropes, for example.

No doubt BT's action will raise eyebrows among those who saw the UK's dominant telco make a fool of itself last year by pursuing its "patent" of hyperlinks.

That challenge - to get US ISPs to cough up for using hyperlinks - was thrown out last year by a US judge who ruled that BT's "hidden page" patent did not cover what we know today as "hyperlinks". BT did not appeal the decision. ®